Thursday, December 13, 2012

Something peculiar about the reporting of North Korea's missile launch

Experts say the launch shows North Korea's rocket has the range to hit Hawaii and parts of the West Coast of the United States. [Emphasis added]

This is odd because the rocket actually got its payload into orbit. If you can get a payload into orbit, then you can get it anywhere in the U.S. (indeed anywhere on the planet) [1], not just the West Coast. Why would a news outlet report such an obvious error? More precisely, who are the "experts" that fed them the erroneous story, and what could possibly have been their motive?

Usually when mainstream news outlets report things that are false or misleading it is not hard to find some plausible political or economic motive behind it, but this is a mystery. There's either something very peculiar about this orbit (in which case that should have been part of the story) or someone along the line just made up the bit about Hawaii and the West Coast out of whole cloth. Why would anyone do that?

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[1] It is not quite true that getting into orbit lets you get anywhere. In general, an orbit constrains you to a certain range of latitudes. The two extremes of this situation are an equatorial orbit, which constrains you to zero degrees latitude, and a polar orbit, which covers all latitudes. Both of these orbits are harder to achieve than an orbit that is inclined at some angle between 0 and 90 degrees.

The only kind of orbit that constrains you in longitude (which is what is being claimed here) is a geosynchronous orbit, and that is very hard to achieve. You have to get to an altitude of 35,000 km or so. The North Korean satellite is in low-earth orbit at about 500km. Not even close.

The actual trajectory of the North Korean satellite seems to be a polar sun-synchronous orbit, which means it could potentially deposit a payload anywhere on earth, including Santa's house.